1. Field of the Invention
This invention relates to novel polyoxyalkylene esters prepared by reacting aryl polycarboxylic acid derivatives (e.g., methyl esters, anhydrides, acid chlorides and free acid) with polyoxyalkylene glycols or methoxy polyethylene glycols. This invention also relates to the use of these polyoxyalkylene esters as durable soil release agents for textiles.
2. Description of the Prior Art
Much effort has been expended in designing various compounds capable of conferring soil release properties to fabrics woven from polyester fibers. These fabrics are mostly copolymers of ethylene glycol and terephthalic acid or dimethylterephthalate. These polyester fabrics tend to be hydrophobic, that is, the ability of water to wet the fabric is reduced, and hinder oil, soil and stain removal during the laundering process. Oil stains tend to bind to the polyester surface which is oleophilic; a number of attempts have been made towards building more hydrophilic character into the polyester fabrics so that release of stains is facilitated during laundering.
Since polyester fabrics are susceptible to oily staining, and once stained, are difficult to clean in an aqueous laundry bath, manufacturers of polyester fibers and fabrics have sought to increase the hydrophilic character of the polyester to provide ease of laundering. For example, attempts to solve the soiling problem by using the only available fluorochemical soil release (3M Company's FC-218) have not been particularly satisfactory because of the high cost and insufficient durability to repeated launderings. The use of non-fluorochemical soil release aids, for example, DuPont's Zelcon TGF, and ICI's Milease T are less costly, but these only provide marginal soil release when compared to the untreated polyester fabric after 5 and 10 launderings. Zelcon TGF also suffers from the added disadvantage of poor shelf stability.
Another approach to the problem of increasing the hydrophilic character of polyester fabrics is illustrated in U.S. Pat. No. 3,959,230. This patent teaches the use of a polymeric soil release agent containing ethylene terephthalate and a polyethylene oxide terephthalate; these polymers contain no free carboxyl nor hydroxy groups; the present invention does. These free carboxyl and hydroxy groups on the fabric tend to impart better soil release properties. The polymers of this patent have a high molecular weight in the range of 25,000 to 55,000; the compound of the present invention has a low molecular weight in the range of 500 to 2,000. The high molecular weight polymers make the fabric stiff and unattractive.
None of the above mentioned prior art compounds comes within the scope of the present invention. The compound of the present invention imparts durable soil release properties to 100% polyester fabric at low add-on levels.